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Moun~ain Coal Compom~ 2000 Annual Hydrology Report West Ei~( Mine • Introduction Purpose The purpose of this 2000 Annual Hydrology Report (AHR) is to summarize Mountain Coal Company's (MCC) hydrologic monitoring activities at the West Elk Mine; report the results of these monitoring activities; and describe the significance of the data, particularly with respect to mining activities as they relate to the Probable Hydrologic Consequences predictions. Overview of 2000 Mining Activities Thermal Event Near the end of January 2000, combustion gases were detected in the mine emanating from the sealed northwest panels. In response, mining operations were ceased and an exploratory drilling program was implemented to define the location and extent of the combustion. Once the areal extent of the thermal event was determined, seals were constructed around the boundary and the area was flooded by injected water from the surface. As a result of the thermal event, no production mining occurred between January 28, 2000 and July 12, 2000. Longwall Mining During water year 2000 (WY00), mining was completed in the eastern half of longwall panels 13 • and the western third of longwall panel 13-A (Map 1). By the end of the water year, the longwall had advanced to 33 cross-cut in longwall panel 13-A. Development Mining Development continued north in the Box Canyon Mains and development of longwall panels 13- A and 14 during WY00 (Map ]). Development in the 14 Tailgate and Headgate proceeded cautiously after the 14SEHG fault was encountered. Hydrologic Characterization of 2000 Water Year Water Year 2000 (WY00) was characterized by below average snowfall at the higher elevations, which resulted in below average streamflows in the North Fork of the Gunnison River and in Minnesota Creek. WY00 precipitation (measured in Paonia) was above average in January, February, June and August and below average in all other months. The variance in WY00 precipitation varied substantially from month to month in comparison to the historic data. October and November precipitation totals were less than 5% of the long-term monthly averages while January was 180% ofthe long-term monthly averages. Climatological Data To summarize precipitation information for the West Elk Mine, data were used from the Paonia, McClure Pass, and Overland Reservoir monitoring stations. Snow data, as well as overall - precipitation for WY00, were compared to long-term averages for these stations to categorize the 531-03?.550 Page 1 Wright Wares Engineers